1. Field of the Invention
The present invention relates to an ion sensor and ion sensor module used to analyze ions contained in a liquid, and a method of manufacturing the ion sensor and, more particularly, to an ion sensor and ion sensor module for analyzing ions contained in human blood or urine, and a method of manufacturing the ion sensor.
2. Description of the Related Art
An ion sensor module calculates the concentrations of electrolytes such as sodium ions, potassium ions, and chlorine ions contained in a sample. The ion sensor module has an ion sensor that senses the potential corresponding to each electrolyte, and a reference electrode device that senses a predetermined potential as the basis of the potential sensed by the ion sensor. The concentration of the electrolyte is calculated on the basis of the potentials sensed by the ion sensor and reference electrode device. The ion sensor and reference electrode device are used as they are attached to an automatic analyzer for analyzing components contained in a sample as objects of biochemistry test items or immunity test items or to an apparatus for exclusively measuring electrolytes.
The ion sensor senses the potential of a responsive portion made of components containing a responsive material which selectively responds to specific ions contained in a sample. The reference electrode device senses a predetermined potential generated with respect to the sample. The concentration of the specific ions is calculated by measuring the electromotive force as a potential difference between the ion sensor and reference electrode device.
As a method of manufacturing an ion sensor that can be made compact, there is a known method that forms a responsive portion by repetitively coating an ion sensor with a small amount of a solution in which a responsive material that responds to ions to be measured is dissolved, and thoroughly drying the solution (e.g., Jpn. Pat. Appln. KOKAI Publication No. 11-295261).
In some cases, however, an air bubble is formed in the coated solution, and this air bubble forms a pore in the responsive portion after the solution is dried. If this pore is formed in the surface of the responsive portion that comes in contact with a sample, a preceding sample remains in the pore and contaminates a sample to be measured next when testing, e.g., a plurality of samples different in concentration, thereby adversely affecting the measurement results. This decreases the yield of ion sensors.